Develop Reference

How do I get an image view to continually move across the screen when a button is held down?

I have searched high and low for an answer to this and can't find one anywhere that works.
For my university assignment i need to create an adventure game in android studio. I want it so when I click down and hold an arrow button (so in the case given its the up button), that the ImageView (player) will continually move across the screen until I release the button. Ive tried OnTouchListeners and mouse events using ACTION_UP and ACTION_DOWN and that works but not for what i need as it still only moves one step when clicked.
ImageView IV_player;
Button ButtonUp;
IV_player = (ImageView) findViewById(R.id.IV_player);
ButtonUp = (Button) findViewById(R.id.ButtonUp);
ButtonUp.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
IV_player.setY(IV_player.getY() - 32);
}
});

Treat your touch listener like a state machine. When an ACTION_DOWN event occurs, start doing whatever action you want to do. When an ACTION_UP/ACTION_CANCEL event occurs stop your action. So how do you go about implementing this?
Your state flag can be a simple boolean:
boolean shouldCharacterMove = false;
Define your touch listener for the view.
ButtonUp.setOnTouchListener(new View.OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
setShouldCharacterMove(true);
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
setShouldCharacterMove(false);
break;
}
return true;
}
});
Before we define setShouldCharacterMove we need to figure out a way to move items. We can do this through a Runnable that runs after X milliseconds.
private final Runnable characterMoveRunnable = new Runnable() {
#Override
public void run() {
float y = IV_player.getTranslationY();
IV_player.setTranslationY(y + 5); // Doesn't have to be 5.
if (shouldCharacterMove) {
IV_player.postDelayed(this, 16); // 60fps
}
}
};
Now we can define setShouldCharacterMove:
void setShouldCharacterMove(boolean shouldMove) {
shouldCharacterMove = shouldMove;
IV_player.removeCallbacks(characterMoveRunnable);
if (shouldMove) {
IV_player.post(characterMoveRunnable);
}
}

Android OnTouchListener Does Not Work

It's simple. The OnTouchListener does not work at all.
I'm fairly certain it's being initialized. I'm using a custom view to draw my UI, and as usual, I'm being impeded by Android's touchy API (pun intended):
public class ViewInterface extends View implements OnTouchListener{
public ViewInterface(Context context){
super(context);
...
}
public void update(){
...
}
#Override
public void onDraw(Canvas canvas){
...
}
#Override
public boolean onTouch(View v, MotionEvent event) {
switch(event.getAction()){
case MotionEvent.ACTION_DOWN:
keyboardEnabled = true;
return true;
case MotionEvent.ACTION_UP:
keyboardEnabled = false;
return true;
default: break;
}
return false;
}
Code for initializing the view in the main activity:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
//setContentView(R.layout.activity_aidan);
activity = this;
viewInterface = new ViewInterface(this);
setContentView(viewInterface);
initializeSpeechRecognition();
findMe();
run.start();
}
What am I missing? Upon touching the screen and holding it, keyboardEnabled should be set to true (its just a debug value) - yet it does not do anything. The touch events don't seem to be responding at all.
I've attempted to use the onTouchEvent method built into View with the following code:
#Override
public boolean onTouchEvent(MotionEvent event) {
switch(event.getAction()){
case MotionEvent.ACTION_DOWN:
keyboardEnabled = true;
return true;
case MotionEvent.ACTION_UP:
keyboardEnabled = false;
return true;
default: break;
}
return false;
}
However this did not work either. The touch events are not responding at all - tapping the screen and releasing should be setting keyboardEnabled to false - which it does not.

You should override the onTouchEvent() method of the View class.
Right now you are simply implementing the OnTouchListener interface which should be used in conjunction with the setOnTouchListener() method.
For example:
#Override
public boolean onTouchEvent(MotionEvent event) {
// do whatever
}
Don't forget to call super where appropriate!
Alternatively, you could call setOnTouchListener(this); somewhere in your code, but that seems redundant.

Double Tap in android View

In a view I want to detect both single tap and double tap. It works fine with me. I can detect both single and double tap. Please find my code
#Override
public boolean onTouch(View view, MotionEvent me) {
// No dragging during animation at the moment.
// TODO: Stop animation on touch event and return to drag mode.
boolean result = true;
result = gestureDetector.onTouchEvent(me);//return the double tap events
if(result)
return false;
switch (me.getAction()) {
case MotionEvent.ACTION_DOWN:
case MotionEvent.ACTION_MOVE:
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
}
private class GestureListener extends GestureDetector.SimpleOnGestureListener {
private String fileName;
#Override
public boolean onSingleTapConfirmed(MotionEvent e) {
// TODO Auto-generated method stub
return false;
}
// event when double tap occurs
#Override
public boolean onDoubleTap(MotionEvent e) {
float x = e.getX();
float y = e.getY();
if(player!=null && player.isPlaying())
{
player.stop();
}
else
{
setFileName(x);
player = new AudioPlayer(fileName);
player.play();
}
return true;
}
}
I am doing some code in Action_UP event. So even when I do a double tap, for the first tap the ACTION_UP event is called and the corresponding code is executed. I want to prevent this from happening. How can I do this. I just want to make sure that the ACTION_UP is called only when the user is done with his gesture. Not immediately after his partial gesture . In this case its being called on finger up of first tap.
How can I make this work in android?
Thanks

According to gesture listener documentation, you need to return true for onSingleTapConfirmed & onDoubleTap. Otherwise the event is not consumed and gestureDetector.onTouchEvent(me); returns false.

How to get click, double tap, and long click gestures for a view inside a gridview?

I have ImageViews inside of a GridView, I had been using an OnItemClickListener along with an OnItemLongClickListener set on the GridView to open the image on a larger page and to delete the item respectively. Now, I have to implement rearranging of the ImageViews in the GridView, so I plan to move the deletion function to a double tap gesture, (please do not lecture me on android style guidelines (including the possibility of contextual actionbars, which I suggested), as this is what my boss asks for to emulate functions inside our ios app) in order to reserve long click for the drag and drop. I set an OnTouchListener on each view in the getView of my custom adapter, feeding a GestureDetecter with a listener extending SimpleOnGestureListener the given MotionEvent with onTouchEvent. I know what to do up to that point, but when I included (onDown of course, to get other callbacks) onDoubleTap, onSingleTapConfirmed, and onLongPressed all taps were interpreted as long clicks. And when I removed the both callback methods to be replaced with their listener counterparts once again (ie OnItemClickListeners) I received those two gestures but not the double tap, which makes sense, as double taps start out as a single tap unless you wait for a bit less than a second to confirm them as singles rather than potential doubles. I also tried placing the OnItemClickListener, but not the OnItemLongClickListener, with the callback in the extended SimpleOnGestureListener. In this case, only long presses were ever interpreted, but other gestures caused no response. Here is my code as it stands now, and do note that I returned false in the onTouchEvent in order to allow others (itemclicklisteners) to consume the events following the attempts made in the GestureDetector.
public class MainBoardGridAdapter extends GenericBoardGridAdapter implements OnItemLongClickListener {
private class Ges extends GestureDetector.SimpleOnGestureListener {
int pos;
public Ges(View v) {
pos = (Integer) v.getTag();
}
#Override
public boolean onDown(MotionEvent me) {
//this does get called but none of these methods below
return true;
}
#Override
public boolean onDoubleTap(MotionEvent me) {
new DeleteConfirmationPrompt(c, "board") {
#Override
protected boolean onDeleteConfirmed() {
// delete the visionboard
return deleteBoard(pos);
}
}; // Constructor shows dialog
return false;
}
#Override
public boolean onSingleTapConfirmed(MotionEvent e) {
MainBoardGridAdapter.super.flagForUpdate(pos);
if (listener != null) {
listener.onBoardClick(pos, getName(pos));
} else {
Intent intent = new Intent(c, VisionBoardActivity.class);
intent.putExtra(VisionBoardActivity.EXTRA_VISION_BOARD_NAME, getName(pos));
frag.startActivityForResult(intent, MyBoardsFragment.REQUEST_EDIT);
}
return false;
}
}
#Override
public boolean onItemLongClick(AdapterView<?> parent, View v,
final int pos, long id) {
Toast.makeText(c, "Long", Toast.LENGTH_LONG).show();
return false;
}
// called by getView of extended adapter
#Override
public void onImageLoaded(ImageView iv, String data, View root) {
iv.setOnTouchListener(new View.OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
(new GestureDetector(c, (new Ges(v)))).onTouchEvent(event);
return false;
}
});
}
}
And in the Activity, gv is my GridView:
gv.setOnItemLongClickListener(gridAdapter);
Also note that I had been using true in the return value in the GestureDetector methods, until trying the current configuration.There was no difference to be seen.
Thank you for your valuable time and help, I hope that someone will be able to point out what I am doing incorrectly.
-Jackson

Android OnLongClickListener not firing on MapView

I just registered an OnLongClickListener on my my MapView on an Android app I'm currently writing. For some reason however the onLongClick event doesn't fire.
Here's what I've written so far:
public class FriendMapActivity extends MapActivity implements OnLongClickListener {
private static final int CENTER_MAP = Menu.FIRST;
private MapView mapView;
private MapController mapController;
//...
private boolean doCenterMap = true;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.friendmapview);
this.mapView = (MapView) findViewById(R.id.map_view);
this.mapController = mapView.getController();
mapView.setBuiltInZoomControls(true);
mapView.displayZoomControls(true);
mapView.setLongClickable(true);
mapView.setOnLongClickListener(new OnLongClickListener() {
public boolean onLongClick(View v) {
//NEVER FIRES!!
return false;
}
});
//...
}
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
switch (keyCode) {
case KeyEvent.KEYCODE_3:
mapController.zoomIn();
break;
case KeyEvent.KEYCODE_1:
mapController.zoomOut();
break;
}
return super.onKeyDown(keyCode, event);
}
#Override
public boolean dispatchTouchEvent(MotionEvent ev) {
int actionType = ev.getAction();
switch (actionType) {
case MotionEvent.ACTION_MOVE:
doCenterMap = false;
break;
}
return super.dispatchTouchEvent(ev);
}
...
}
May overlays which I'm adding cause the problem?? Any suggestions?

I ran into the same problem and there is a simple solution to your problem actually; it's because you're using the wrong type of listener.
You should use the OnMapLongClickListener() object from the OnMapLongClickListener interface.
Hopefully everything should work properly :)
Please tell me if it works.

I just ran into this problem. I tried the solution above, but it doesn't quite work 100% in that we want the long press action to fire, even if the user is still holding a finger down.
This is how I implemented a solution, using a handler and a delayed task -
As a side note, I used a similar type implementation, but in reverse, to hide/show zoom controls on touch/etc..
private Handler mHandler = new Handler();
private final Runnable mTask = new Runnable() {
#Override
public void run() {
// your code here
}
};
#Override
public boolean onTouchEvent(MotionEvent ev) {
if (ev.getAction() == MotionEvent.ACTION_DOWN) {
// record the start time, start the timer
mEventStartTime = ev.getEventTime();
mHandler.postDelayed(mTask, LONG_PRESS_TIME);
} else if (ev.getAction() == MotionEvent.ACTION_UP) {
// record the end time, dont show if not long enough
mEventEndTime = ev.getEventTime();
if (mEventEndTime - mEventStartTime < LONG_PRESS_TIME) {
mHandler.removeCallbacks(mTask);
}
} else {
// moving, panning, etc .. up to you whether you want to
// count this as a long press - reset timing to start from now
mEventStartTime = ev.getEventTime();
mHandler.removeCallbacks(mTask);
mHandler.postDelayed(mTask, LONG_PRESS_TIME);
}
return super.onTouchEvent(ev);
}

In the mean time I found the "solution" (or workaround, call it as you like) by myself. The way I worked through this issue is by using a GestureDetector and forwarding all touch events to that object by implementing an according OnGestureListener interface.
I've posted some code on my blog if anyone is interested:
http://juristr.com/blog/2009/12/mapview-doesnt-fire-onlongclick-event/
Don't ask me why this didn't work by hooking up the OnLongClickListener directly on the MapView. If someone has an explanation let me know :)
UPDATE:
My previously suggested solution using a GestureDetector posed some drawbacks. So I updated the blog post on my site.

In WebView framework code performLongClick() is used to handle long press event, this is how Android copy Text Feature is implemented in Browser, that is why onLongClick is not been fired.